public class Triangle {
    double a, b, c;
    Triangle(double a, double b, double c){
        this.a = a;
        this.b = b;
        this.c = c;
    }

    double calArea(){
        double p = (a + b + c) / 2.0;
        return Math.sqrt(p * (p - a) * (p - b) * (p - c));
    }

    boolean isTri(){
        return a + b > c && a + c > b && b + c > a;
    }
}
